What the Anesthesiologist Should Know before the Operative Procedure

Gallbladder disease affects more than 20 million individuals in the United States annually and is one of the most common medical conditions leading to a surgical intervention. Risk factors for gallbladder disease include gender, ethnicity, and comorbidities. Cholelithiasis is also related to diet and genetic factors and is more common in Hispanics, Native and South Americans, and Northern Europeans. In women, cholelithiasis is common during pregnancy, and postmenopausal use of hormone replacement therapy is associated with a 2- to 3-fold increase in incidence. A mutation of the ABCG8 gene increases the risk of cholelithiasis.

In cholecystitis, the wall of the gallbladder becomes inflamed, resulting in abdominal pain, fever, and nausea and vomiting. Severe cases may be associated with ascending cholangitis and jaundice, and in extreme cases necrosis and rupture of the gallbladder with resultant peritonitis may result in septic shock.

It is estimated that 500,000 cholecystectomies are performed annually and laparoscopic cholecystectomy is currently the gold standard in operative management. Laparoscopic cholecystectomy was first described in 1987 by Erich Muhe, a German surgeon, and introduced to the United States in 1988 by Reddick and Olsen of Nashville, Tennessee. The procedure now accounts for 80%-83% of cholecystecomies performed in the United States each year. The indications for the surgery include cholecystitis and cholelithiasis.

Perioperative mortality associated with laparoscopic cholecystectomy is <1% and reported morbidity ranges from 2.1% to 17%. Rates of conversion from laparoscopic to open cholecystectomy vary from 1% to 6.9%. Most laparoscopic cholecystectomies are performed on an outpatient basis, resulting in a reduction in the total cost of care per patient by decreasing the length of postoperative hospitalization.

Laparoscopic cholecystectomy involves intraperitoneal insufflation of carbon dioxide through a Veress needle inserted into the infraumbilical region of the abdomen, followed by introduction of cannulas to accommodate the surgical instruments. The pneumoperitoneum is maintained with carbon dioxide gas delivered by a variable flow insufflator that is preset to maintain the intra-abdominal pressure at 12-15 mm Hg. The surgeon uses a laparoscope fitted with a video camera and a monitor system to visualize the surgical field while manipulating the instruments. Intraoperatively the patient is placed in steep reverse Trendelenburg position, with a left lateral tilt to facilitate visualization and dissection of the gallbladder.

1. What is the urgency of the surgery?

Emergent: Gallbladder perforation is a life-threatening complication of cholecystitis and results in diffuse peritonitis. Early diagnosis and emergency surgery are of crucial importance.

Urgent: Ascending cholangitis is a medical emergency usually related to biliary obstruction due to cholelithiasis. It requires urgent intervention with hydration, antibiotics, and endoscopic retrograde cholangiopancreatography (ERCP) to relieve the obstruction. Chloecystectomy is delayed until acute symptoms have resolved.

An uncertain diagnosis is also an indication for delay of elective surgery. Laboratory tests are nonspecific and may not aid in diagnosis. In the elderly, especially, delay in surgery has been shown to be an independent predictor of morbidity and mortality.

What is the risk of delay in order to obtain additional preoperative information?

Early open cholecystectomy was the established standard of care for the treatment of acute cholecystitis, in order to reduce mortality and morbidity and total duration of hospitalization. However, appropriate timing for laparoscopic cholecystectomy is controversial. The current professional consensus is that early laparoscopic cholecystectomy is preferable since delayed surgery is associated with the risk of failure of conservative therapy, as well as increased hospital stay and medical costs. Delayed surgery is also associated with the risk of cholelithiasis-related complications and surgical difficulties due to fibrosis and adhesions. A recent meta-analysis of four studies with a total of 375 patients with acute cholecystitis suggested that early laparoscopic cholecystectomy was associated with longer operative time but reduced total duration of hospital stay and no difference in overall postoperative morbidity rates compared with delayed surgery.

2. Preoperative evaluation

The purpose of preoperative evaluation is to identify patients at risk for adverse perioperative events and implement strategies to reduce postoperative morbidity and mortality. Preoperative investigations should be performed if the results will have an impact on perioperative management. Liver function tests in patients with cholecystitis may reveal abnormalities as a result of biliary obstruction, while pancreatic damage may result in diabetes mellitus.

Medically unstable conditions warranting further evaluation include:

Well-documented coronary heart disease associated with angina after strenuous exercise usually does not need any additional preoperative workup. In contrast, a patient with dyspnea on mild exertion is at high risk for developing perioperative ventricular dysfunction, myocardial ischemia, and possible myocardial infarction (MI) and should have preoperative stress testing.

Severe valvular heart disease is a predictor of cardiac risk. The decision regarding surgery such as laparoscopic cholecystectomy in these patients requires a consideration of the risks and benefits of the diagnostic and therapeutic interventions and the surgery. Patients with significant valvular disease can undergo noncardiac surgery safely with intensive perioperative anesthetic management.

Indications for delaying surgery include:

The presence of acute/unstable cardiac conditions including unstable angina, acute MI within the past 7 days, or an MI within 8-30 days with symptoms of decompensated congestive heart failure increases the risk for cardiac morbidity and mortality in the perioperative period and warrants postponement of elective surgery.

3. What are the implications of co-existing disease on perioperative care?

The presence of coexisting disease is an important predictor of postoperative mortality and morbidity. The American Society of Anesthesiologists' Physical Status, age, surgical procedure, and emergent surgery are significant predictors. A history of two coexisting diseases, especially congestive heart failure and renal disease, is also a predictor of adverse outcomes.

b. Cardiovascular system

There are several studies that have shown an increased risk for ischemic heart disease in patients with gallbladder disease. Women with gallbladder disease have a relative risk of 6.6 for MI. This is probably due to the common risk factors associated with coronary heart disease and cholelithiasis.

Perioperative evaluation

The American College of Cardiology and American Heart Association (ACC/AHA) have clear cut guidelines for cardiac evaluation of the patient scheduled for noncardiac surgery. Several studies have shown that these guidelines are both clinically useful and cost effective.

Identification of clinical risk factors by patient history is a better predictor of perioperative cardiac complications than the preoperative electrocardiogram (ECG) in patients over 50 years of age undergoing noncardiac surgery. In this age group abnormalities are noted in 45% of ECGs, and while right and left bundle branch blocks are associated with postoperative MI and death, they do not have any added predictive value over clinical risk factors. Ambulatory laparoscopic cholecystectomy is usually low-risk surgery with a low risk of cardiac complications, and patients without active cardiac conditions and average exercise capacity do not need any cardiac testing preoperatively.

Clinical predictors (derived from the Revised Cardiac Risk Index or RCRI) that alter these recommendations include ischemic heart disease, congestive heart failure, cerebrovascular disease, diabetes, and renal insufficiency. Patients with one or two of these predictors can proceed for laparoscopic cholecystectomy if their heart rate is controlled, or undergo further noninvasive cardiac testing if it will alter perioperative management.

Noninvasive tests of myocardial perfusion include exercise or pharmacologic stress testing. The exercise stress test is the least invasive and most cost effective method for detecting ischemia. However, most surgical patients are unable to exercise to an adequate level. The likelihood of a cardiac adverse event with a positive dobutamine stress echocardiogram or dipyridamole thallium imaging is low (negative predictive value of 100% and positive predictive value of 20%).

Other noninvasive tests to evaluate myocardial function include transthoracic echocardiography and radionuclide scanning. The assessment of left ventricular ejection fraction (LVEF) by these tests is not a sensitive predictor of perioperative cardiac risk. However, the clinical risk factors identified by RCRI are better predictors, with cardiac event rates of 0.4%, 0.9%, 7%, and 11% with 0, 1, 2, or 3 or more risk factors respectively. Therefore, patients with 2 or more risk factors should be considered at high risk.

Perioperative risk reduction strategies

Percutaneous coronary revascularization prior to noncardiac surgery does not prevent perioperative cardiac events except in patients with acute coronary syndrome. Optimal medical management in multivessel disease has been shown to be superior to revascularization in nonsurgical patients. Noncardiac surgery following revascularization is associated with increased perioperative morbidity and mortality.

If preoperative revascularization is necessary in patients who will need noncardiac surgery within 12 months, percutaneous intervention without stenting or with bare metal stents (BMS) should be considered, rather than the drug-eluting stents (DES) because of the anticoagulation requirements. Antithrombotic treatment with clopidogrel is required for 4-6 weeks in the case of BMS and at least 1 year with DES, along with lifetime low-dose aspirin. The current guidelines indicate that noncardiac surgery should be delayed for at least 2 weeks and ideally for 4-6 weeks following insertion of BMS, and there are no firm guidelines for DES.

Coronary artery bypass grafting (CABG) is not recommended before noncardiac surgery unless cardiac symptoms are unstable and CABG is justified on the basis of long-term outcome. CABG significantly reduces the risk of adverse cardiac events following subsequent noncardiac surgery in patients who are symptom free and have good left ventricular function, but noncardiac surgery should be delayed for at least 30 days.

The ACC/AHA recommendations for perioperative beta-blockers in low-risk surgery are to continue the drugs in those patients who are already taking them. Starting beta-blockers, especially in patients with low cardiac risk, is controversial. Administration of low-dose, long-acting beta-blockers titrated to effect at least 7 days prior to surgery is associated with improved cardiac outcomes with no increased risk of stroke. While acute administration of large-dose metoprolol is associated with reduction in the incidence of cardiac death, MI, and cardiac arrest, the overall mortality rate and incidence of stroke are increased.

In patients on dual antiplatelet therapy after stent placement, the risk of acute stent thrombosis due to perioperative hypercoagulability versus the increased risk of major surgical bleeding must be considered. When the risk of bleeding is minimal, dual antiplatelet therapy should be continued. If the risk of bleeding is significant and it is deemed necessary to stop therapy, clopidogrel must be discontinued 7 days prior to surgery and it should be restarted on the first postoperative day if possible, with an initial loading dose followed by the usual maintenance dose. Whenever possible, aspirin should be continued perioperatively.

c. Pulmonary

Risk factors for postoperative pulmonary complications include chronic pulmonary disease, cigarette smoking, anesthetic time of 180 minutes or longer, and emergency surgery. Smokers have an increased risk of gallbladder disease. In a large series of veterans, predictors of postoperative respiratory failure included age over 60 years, low serum albumin level (<30 g/L), renal insufficiency (BUN >30 mg/dL), prior history of COPD, and smoking.

COPD

Perioperative evaluation

Numerous studies have shown that patients with preexisting pulmonary disease, specifically COPD, are at increased risk for postoperative pulmonary complications. The increased incidence of postoperative pulmonary complications in patients with COPD is caused by the combination of the pulmonary pathophysiology and comorbidities, often cardiac disease. Although laparoscopy causes less pulmonary compromise in comparison to laparotomy, upper abdominal laparoscopy is associated with dysfunction of the diaphragm.

Preoperative pulmonary function testing may identify patients at increased risk for pulmonary complications. The patients with COPD typically have a reduction in the forced vital capacity in 1 second on spirometry. The degree of preoperative oxygen desaturation can be readily assessed noninvasively using pulse oximetry, and monitoring of transcutaneous carbon dioxide tension has recently been introduced into clinical practice and allows noninvasive evaluation of hypercarbia and respiratory insufficiency.

Patients with COPD must be screened for pulmonary hypertension and cor pulmonale. The chest radiograph will reveal right ventricular hypertrophy, right atrial dilatation, and prominent pulmonary artery, with reduced vascular markings in the peripheral lung fields, while right ventricular hypertrophy-right-axis deviation, prominent R wave in lead V1, and inverted T waves in right precordial leads are typical ECG findings. On echocardiogram, right ventricular dilatation and tricuspid regurgitation are likely findings.

Perioperative risk reduction strategies

Preoperatively, patients should be carefully screened for preexisting pulmonary infections that must be treated prior to surgery. Many of these patients have an element of bronchospasm and may benefit from a course of bronchodilators and steroids. Patients with cor pulmonale will need medical optimization preoperatively. In patients who are chronically hypoxemic, oxygen administration should be started preoperatively and surgery deferred until pulmonary hypertension improves.

Reactive airway disease (asthma)

Perioperative evaluation

Risk factors for postoperative pulmonary complications can be determined from the patient’s history and include recent exacerbations, emergency room visits or hospitalizations, tracheal intubation, and mechanical ventilation.

Chest radiograph will reveal flattening of the diaphragm in the case of hyperinflated lungs. Pulmonary function tests can be used to assess the extent of the obstructive and restrictive disease and response to bronchodilators. While the forced expiratory volume in 1 second (FEV1) after bronchodilator therapy is an indicator of the severity of pulmonary impairment, the test is effort dependent and may not be totally accurate. Measurement of oxygen saturation by pulse oximetry is a convenient method for detecting pulmonary compromise and hypoxemia preoperatively.

Perioperative risk reduction strategies

Respiratory infections can trigger an acute asthma attack and must be treated preoperatively. However, increased airway reactivity may persist for several weeks after resolution of the infection. Patients with poorly controlled asthma symptoms will require beta-adrenergic stimulants and inhaled and/or oral glucocorticosteroids.

Stress is known to precipitate asthmatic symptoms and patients with mild asthma and anxiety may benefit from the use of preoperative sedatives. Oral benzodiazepines have been shown to decrease airway contractility, in vitro; however, they are associated with dose-dependent respiratory depression and should not be used in patients with severe disease.

d. Renal-GI:

Renal disease

Perioperative evaluation

Approximately15% of the US population has chronic renal disease (CRD). CRD has been associated with increased morbidity and mortality following several types of surgery. These patients usually have several comorbidities including diabetes, coronary heart disease, hypertension, and anemia, which must be carefully evaluated preoperatively. It is important to control blood pressure preoperativelysince it has been shown that mean arterial pressures greater than 110 mm Hg are associated with significant intraoperative fluctuations.

Anemia is common in CRD and may necessitate preoperative transfusion or supplementation with iron or erythropoietin.

Patients with CRD often have significant electrolyte imbalance and mild to moderate hyperkalemia is common. It is generally recommended that serum potassium levels be no higher than 5-5.5 mEq/L preoperatively.

Perioperative risk reduction strategies

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II antagonists (ARAs) are commonly used to treat hypertension. However, these drugs may be associated with intraoperative hypotension and it is usually recommended that they be discontinued 10 hours prior to surgery.

Patients on hemodialysis should have their surgery within 24 hours of therapy in order to minimize the risk of electrolyte imbalance and fluid shifts. Pneumoperitoneum during laparoscopy is associated with reduction in renal perfusion andthe intra-abdominal pressure should be maintained below 15 mm Hg in order to preserve renal blood flow.

While adequate analgesia is important following surgery, these patients are prone to respiratory depression due to impaired excretion of the opioids. Nonopioid analgesics should be used to decrease the dose of opioid analgesics required. Nonsteroidal anti-inflammatory agents are not recommended in patients with renal insufficiency.

Gastroesophageal reflux disease

Approximately 10%-20% of adults in the United States are affected by gastroesophageal disease (GERD). The major physiological derangement in GERD is a reduction in lower esophageal sphincter(LES) tone.

Perioperative risk reduction strategies

The incidence of aspiration during anesthesia in adults is in the range of 3.1 per 10,000 patients. Not all patients with GERD are at risk for aspiration, since regurgitation of gastric contents occurs due to an increase in intragastric pressure coupled with the decrease in LES tone. Measures to minimize the risk of regurgitation and aspiration involve reduction of the volume and acidity of gastric contents with preoperative starvation, use of proton pump inhibitors, and H2 antagonists.

e. Neurologic:

Acute issues

Patients with newly diagnosed neurologic conditions or recent exacerbations of existing conditions should not have elective surgery until the acute condition is treated and resolved.

Chronic disease

Perioperative preparation varies with the type of neurologic condition and any existing comorbidities.

a. Cerebrovascular disease

A large proportion of patients with neurologic disease have a history of previous hemorrhagic or ischemic vascular accident. These patients may have comorbidities, including hypertension, coronary artery disease, and diabetes. Patients with previous cerebrovascular accidents (CVAs) are at a high risk for perioperative CVA. In these patients, it will be important to know the details of the existing neurologic deficits and vascular abnormalities. Perioperatively, it is important to maintain blood pressure as close to baseline in order to maintain adequate cerebral perfusion and to continue prophylactic anticoagulant therapy.

b. Spinal disease

Chronic nerve root or spinal cord compression may be related to degenerative disc disease, arthritic changes, and congenital or traumatic conditions. The type and level of the neurologic deficit will determine the focus of preoperative assessment. Scoliosis and ankylosing spondylitis may result in pulmonary impairment, and patients with cervical lesions may require special measures to stabilize the neck while securing the airway. In patients with lesions above T6, the anesthesiologist must be prepared to treat autonomic hyperreflexia. Many patients with spinal cord pathology suffer from chronic pain and may be on chronic opioid therapy or adjuvant analgesics. These medications should be continued perioperatively to prevent withdrawal symptoms; however, altered pain sensitivity and drug tolerance may complicate postoperative analgesic therapy.

c. Seizure disorders

Seizures are associated with anatomic and metabolic conditions and it is important to determine the type of disorder and its etiology preoperatively. Antiepileptic drugs must not be interrupted during the perioperative period. Because many of these drugs are hepatotoxic, liver function should be evaluated preoperatively since hepatic dysfunction may alter the choice of anesthetic agents.

f. Endocrine:

Diabetes mellitus

The prevalence of gallbladder disease tends to be higher in diabetics than in nondiabetics and the incidence tends to be higher in older, obese female diabetics. In females, a direct correlation has been noted between serum insulin, C-peptide, and gallbladder disease. Cholecystitis is a more serious disease in diabetics who frequently develop gangrenous cholecystitis, emphysematous cholecystitis, and gallbladder perforation. For this reason, cholecystectomy has been recommended in asymptomatic diabetics with cholelithiasis. Diabetic patients have been noted to have a higher rate of operative complications with laparoscopic cholecystectomy and a higher rate of conversion to laparotomy.

Diabetic patients have a higher incidence of perioperative cardiac events. In severe disease, autonomic dysfunction may be present and these patients may not experience chest pain with myocardial ischemia. Diabetics have a high incidence of renal failure, and preoperative assessment of renal function will identify patients at risk for altered pharmacokinetics of insulin and renally excreted anesthetic/analgesic agents.

The Society for Ambulatory Anesthesia (SAMBA) has recently published guidelines for perioperative management of the diabetic outpatient. Tight glycemic control has been shown to be detrimental in critically ill patients; instead, the perioperative goal should be to maintain the blood glucose above 80 mg/dL and below 200 mg/dL. Oral hypoglycemic agents need not be stopped prior to surgery unless the patient has renal disease or intravenous contrast use is anticipated, and the drugs should be restarted as soon as oral intake is resumed. Diabetic patients on insulin therapy who undergo laparoscopic cholecystectomy will need minimal alteration of their basal insulin on the day of surgery. Additional subcutaneous dosing with rapid-acting insulin has been recommended for control of blood glucose in the perioperative period.

Thyroid dysfunction

Hypothyroidism affects 1% of Americans, usually females. The disease may result in myocardial depression and an increased peripheral vascular resistance. The response to hypoxemia and hypercarbia is altered. These patients are usually on levothyroxine replacement that should be taken preoperatively. Most patients undergo surgery without any significant adverse events, although they are very sensitive to sedatives and opioids, which should be used judiciously.

Myxedematous coma is a medical emergency and elective surgery should be postponed until the patient has been stabilized. Therapy usually involves intravenous levothyroxine, glucocorticoids, and volume resuscitation.

Hyperthyroidism affects many organ systems including the cardiovascular and the gastrointestinal systems. Patients on antithyroid drugs should take their medications during the perioperative period. Patients with uncontrolled or poorly controlled disease should have elective surgery postponed until they are medically stable. In the case of urgent or emergent surgery in the inadequately controlled patient, beta-blockers and intravenous antithyroid drugs may be needed. These patients may develop thyroid storm during the perioperative period and will have to be monitored in an acute care setting for 48 hours, since this condition is associated with a high mortality rate.

Adrenal insufficiency

The most common cause of adrenal suppression is exogenous administration of steroids. Steroid-induced adrenal insufficiency is unlikely unless patients have received the equivalent of 20 mg of prednisone for more than 2 weeks within 6 months of surgery, in which case a short-acting steroid should be administered in the perioperative period, usually for 48 hours. Topical, inhaled, and regional glucocorticoids may also result in adrenal suppression.

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (eg. musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

Obesity

One third of Americans suffer from obesity, defined as a body mass index (BMI) of 30 kg/m2 or higher. Many patients scheduled for laparoscopic cholecystectomy are obese since excessive body weight is an independent risk factor for gallbladder disease. Obese patients have a higher incidence of perioperative complications, and those who weigh more than 115 kg also have an increased surgical mortality rate.

Obese patients may present a challenge with respect to airway management and should have a thorough airway examination preoperatively. Predictors of difficult mask ventilation have been noted to include age >55 years, BMI >26 kg/m2, lack of teeth, a beard, and a history of snoring. There have been several studies demonstrating that obesity alone is not a predictor of difficult laryngoscopy or intubation. However, a neck circumference >40 cm increases the odds ratio of difficulty intubation by 1.13 for each 1 cm.

Although obese patients typically have restrictive pulmonary impairment, with reduction in the expiratory reserve volume, functional residual capacity, total lung volume, and compliance, preoperative spirometry is not indicated prior to laparoscopic cholecystectomy. Similarly, a preoperative chest radiograph is not useful either. In patients who may have COPD or obesity hypoventilation syndrome, the degree of hypoxemia may be measured with pulse oximetry. Other clues to chronic hypoxemia may be polycythemia, hypercarbia, and an elevated serum bicarbonate level. These patients may require further workup with chest radiograph to determine cardiomegaly, ECG to screen for left ventricular hypertrophy, and echocardiography to evaluate myocardial function and presence of pulmonary hypertension.

Obese patients with and without obstructive sleep apnea (OSA) are prone to develop hypoxemia postoperatively. While the gold standard for diagnosing OSA is a polysomnogram (PSG), the STOP BANG questionnaire has been validated and correlates with the apnea hypopnea index of the PSG.

Patients who have been prescribed a CPAP device should have it applied postoperatively once they are awake and do not have nausea and/or vomiting.

4. What are the patient's medications and how should they be managed in the perioperative period?

Nonprescription drugs, herbal preparations, and vitamins

Many patients who present for surgery are chronically on aspirin for its antithrombotic effects. Aspirin is an irreversible inhibitor of platelet cyclooxygenase (COX) and can cause increased intraoperative bleeding. The platelets are replaced every 7-10 days and it is necessary to stop aspirin for 1 week prior to surgery. NSAIDs, on the other hand, are reversible COX-2 inhibitors and platelet function normalizes 24 hours after the last dose.

Approximately one third of surgical patients use herbal supplements. Many of these drugs have side effects that pose serious risks in the perioperative period. Ginkgo biloba inhibits platelet activating factor and can cause bleeding; it should be stopped 36 hours prior to surgery. Garlic, ginger, and ginseng inhibit platelet aggregation, may augment the effects of anticoagulants and NSAIDs, and should be stopped 7 days before surgery.

Echinacea can cause immune system and hepatic dysfunction and is often discontinued before surgery. Ephedra has been associated with tachycardia, hypertension, myocardial infarction, and stroke. It may cause arrhythmias with volatile anesthetics and, if taken for a long period, can deplete endogenous catecholamines. Patients may require direct-acting agents to treat hypotension. Ephedra should be stopped 24 hours before surgery. Kava causes sedation and potentiates the effects of benzodiazepines and barbiturates; it should be stopped 24 hours before surgery. Patients who use kava may exhibit withdrawal symptoms on stopping the drug. Valerian also has sedative properties that may potentiate the effects of anesthetic drugs. St John's wort is an inducer of cytochrome P450 enzymes and should be discontinued 5 days before surgery.

Fish oil and vitamin E are associated with a risk for increased bleeding; it is recommended that they be stopped 10 days prior to surgery.

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

The definitive treatment of gallbladder disease is cholecystectomy. Supportive measures prior to surgery may include broad-spectrum antibiotics, analgesics, and intravenous fluid resuscitation.

i. What should be recommended with regard to continuation of medications taken chronically?

A large number of surgical patients are on numerous therapeutic drugs. It has been found that there is a higher incidence of perioperative complications among patients who take medications and that there is a significant association between abstinence from therapeutic medication and perioperative adverse outcomes. It has been suggested that, whenever possible, patients be allowed to continue their chronic medications until the day of surgery, and alternatives to the oral route be used until the oral route is reestablished following surgery. When alternative routes of administration are not available for the medication, then an alternative drug that can be administered by a non-oral route should be substituted.

Cardiac drugs

Calcium channel blockers are widely used antihypertensive drugs and have been shown to reduce the risk of perioperative stroke and myocardial infarction. They should not be discontinued preoperatively.

The advantages of continuation of beta-blockers during the perioperative phase are well documented. It is essential that these drugs be continued in patients at risk for myocardial ischemia. Antianginal drugs (nitrates) and antiarrhythmic therapy must not be stopped preoperatively. The management of cardiac glycosides is controversial, but most experts recommend continuation through the day of surgery to provide cardiac stability.

ACE inhibitors are used to treat hypertension, coronary artery disease, and congestive heart failure. The duration of effect of enalapril and lisinopril is 30 hours, and 6-14 hours for captopril. Patients who receive these drugs on the morning of surgery have been noted to have significant hypotension on induction of anesthesia and it is recommended that these drugs be stopped. It is generally accepted that 3-5 elimination half-lives of a drug must elapse for significant reduction in plasma concentration of the drug.

Angiotensin receptor antagonists are common antihypertensive drugs and also have been associated with severe hypotension on induction that may not respond to standard vasopressors (ephedrine or phenylephrine) and may require vasopressin. It is recommended that these drugs be withheld on the day of surgery.

Pulmonary medications

Patients with asthma and COPD should continue their inhaled beta agonists, inhaled ipratropium, leukotriene inhibitors, and corticosteroids. It is recommended that they bring their medications to the hospital and use them prior to surgery. Theophylline has a central stimulatory effect on respiration in addition to its bronchodilator action and should be continued during the perioperative period in the patient with COPD.

Renal medications

Patients on hemodialysis should be dialysed the day before surgery to optimize fluid and electrolyte status. Elective surgery should be avoided on the day of surgery to avoid rebound anticoagulation, fluid shifts, and hypokalemia. If surgery is delayed more than 48 hours after hemodialysis, the patient may develop fluid overload, hyperkalemia, and acidosis.

Renal transplant recipients may be on immunosuppressive therapy, which usually includes three drugs: immunophilin binding drugs cyclosporine A, FK506 (tarolimus), and rapamycin (sirolimus) prevent cytokine-mediated T-cell activation and proliferation.

Steroids block the production of inflammatory cytokines and lyse/alter function of T lymphocytes.

It is important to maintain immunosuppressive therapies at all times. However, the risk of infection is increased and the dose of these medications may be reduced perioperatively. Drug interactions are common, and the relationship between immunosuppressive drugs and antibiotic and anesthetic drugs is no exception. Many immunosuppressive drugs (cyclosporine, FK506) are metabolized by the cytochrome P450 system and the effects of anesthetic drugs may be prolonged, rather than pronounced.

Neurologic medications

Levodopa is the cornerstone of therapy for parkinsonism, in combination with carbidopa – a decarboxylase inhibitor. It has a short elimination half-life (1-3 hours) and should be given on the day of surgery to prevent muscle rigidity. Anticonvulsants also must be continued during the perioperative period.

Antiplatelet medications

Most ambulatory surgeries are not associated with major bleeding risk and antiplatelet therapies do not pose an additional hazard. Aspirin and clopidogrel are the most commonly used combination of inhibitors. Aspirin, clopidogrel, and prasugrel have irreversible effects that last for the lifetime of the platelets. Ticagrelor, on the other hand, is associated with a reversible inhibition and a rapid offset of effect. In patients with coronary artery stents, it will be necessary to contact the cardiologist to assess the risk of stent thrombosis. Interruption of clopidogrel for 5 days is usually sufficient to reduce the risk of bleeding, while aspirin therapy should be continued. Clopidogrel should be resumed the day after surgery as long as there are no concerns of bleeding.

Psychiatric medications

Tricyclic antidepressants are the most common drugs used to treat depression. They inhibit the reuptake of norepinephrine and serotonin. These drugs are continued through the perioperative period to prevent acute exacerbation of psychiatric symptoms. The monoamine oxidase (MAO) inhibitors cause an irreversible inhibition of the metabolism of the amines and chronic therapy results in a reduction of neurotransmitters. These drugs are continued preoperatively; however, patients may develop hyperpyrexia, muscle rigidity, seizures, and coma if they receive opioids concomitantly (neuroleptic malignant syndrome).

Lithium is used to treat bipolar disorders and decreases the release of neurotransmitters. Nondepolarizing neuromuscular blocking agents may have a prolonged effect in patients on this drug. It is usually recommended that it be stopped for 24-48 hours prior to surgery.

j. How To modify care for patients with known allergies -

The incidence of severe anaphylaxis during general anesthesia ranges from 1:6000 to 1:10,000, and mortality results in 3%-6% of cases. The most common cause is neuromuscular blocking agents (60%-70%), followed by latex (10%-20%), antibiotics (5%-20%), and colloids and induction agents (3%-5%). Most anesthetists encounter serious allergic responses rarely and an increased awareness of the clinical manifestations of allergic responses and the use of a structured approach to diagnosis and management improves clinical outcomes. In patients with a known allergy, the triggering agent and related drugs should be avoided as there may be cross reactivity. Pretreatment with corticosteroids and H1 and H2 blockers has been recommended.

Cutaneous reactions are the most common manifestation of anaphylactoid reactions (93.7%), while cardiovascular collapse (50.8%) and bronchospasm (39.8%) are more common in anaphylactic reactions. Any unexpected sudden and severe hypotension or bronchospasm during anesthesia should be considered an anaphylactic reaction and treated aggressively with intravenous epinephrine. A large dose of epinephrine may be required, with an infusion to follow, which should be titrated to heart rate and blood pressure.

All patients who are suspected of having an allergic reaction should have plasma histamine tryptase and specific IgE levels measured at the time of the reaction and at 1 and 6 hours after the reaction. Skin testing should be performed at 6 weeks following the episode. Patients should be instructed to wear a Med-Alert bracelet.

The incidence of latex allergy ranges from 1% to 6% in the general population and 8% to 12% in health care workers. All patients must be queried about latex sensitivity, and avoidance of contact with latex products is mandatory for patients who report sensitivity. Patients must have wristbands to identify their allergy and all perioperative staff must be made aware of the patient’s allergy.

Preoperative and postoperative areas must remove all latex products to prevent accidental exposure. All anesthetic equipment must be latex free, including face masks, rebreathing bags, ventilator bellows, breathing circuit, and blood pressure cuffs. The operating room must have a cart with latex-free surgical supplies for intraoperative use.

Appropriate signage should be posted on the entry to the operating room, on the patient’s chart, and at the patient’s bed to inform all health care workers of the patient’s latex allergy. Adequate supplies of resuscitative drugs must be available. Bottles with rubber stoppers must be opened to withdraw the drug rather than puncturing the rubber stopper with a needle, since this may result in release of latex proteins from the stopper.

l. Does the patient have any antibiotic allergies-

Penicillin and cephalosporins are the most common cause of antibiotic-induced anaphylaxis. The skin tests for these agents are highly sensitive and specific; however, of the many people who are classified as penicillin-allergic, 80%-90% do not react to skin testing. Once penicillin allergy is documented, likelihood of cross sensitivity must be considered.

A wide range of cross sensitivity between penicillins and carbapenems has been reported, but when it is verified with skin testing, it is approximately 1%. The choice of antibiotics in the penicillin allergic patient is not easy, but Aztreonam is a monobactam that has been studied extensively and immunogenic studies indicate that it does not cross react with penicillin or cephalosporin antibodies, except ceftazidine, making it a suitable alternative.

Anaphylaxis due to vancomycin is rare, but rapid administration may result in a nonspecific histamine release resulting in “red man syndrome.”

m. Does the patient have a history of allergy to anesthesia?

The incidence of severe anaphylaxis during general anesthesia ranges from 1:6000 to 1:10,000, and mortality results in 3%-6% of cases. The most common agents associated with perioperative anaphylaxis are the neuromuscular blocking agents (NMBAs), followed by latex and antibiotics. Dyes and contrast agents, sedatives-hypnotics, opioids, local anesthetics, colloid solutions, aprotinin, protamine, and chlorhexidine have been associated with allergic responses.

5. What laboratory tests should be obtained and has everything been reviewed?

Discovery of most abnormal laboratory tests does not alter perioperative outcomes. Laparoscopic cholecystectomy is a relatively low-risk procedure and patients with known stable, chronic diseases are unlikely to benefit from any “routine” preoperative laboratory tests. Patients with acute cholecystitis are likely to have abnormal laboratory values compared with those with chronic disease. Laboratory tests should be ordered only if the results will impact the decision to proceed with the planned procedure or alter the anesthetic management.

Hemoglobin

The prevalence of anemia on routine preoperative screening is in the range of 1.8%. In older patients, this incidence is 4%-9%. The current practice of requiring a preoperative hemoglobin level of 10 g/dL or greater is based on anecdotal reports and cohort studies. However, baseline preoperative hemoglobin values do predict the need for intraoperative transfusions and preoperative hemoglobin determination is indicated in surgeries associated with significant blood loss or in patients with a history suggestive of anemia.

Laparoscopic cholecystectomy is not usually associated with significant bleeding and lower preoperative hemoglobin values are acceptable. Normal healthy patients are able to tolerate hemoglobin levels between 7 and 8 g/dL. Asymptomatic, reversible ST-segment changes have been noted at hemoglobin levels of 5-7 g/dL, which worsen at levels of 5-6 g/dL. At these low levels minor cognitive changes are encountered in healthy patients. Patients with significant cardiorespiratory disease may not tolerate low levels of hemoglobin as well and may require preoperative correction of anemia.

Electrolytes

Measurement is rarely required in healthy patients scheduled to undergo laparoscopic cholecystectomy. Patients with renal or endocrine disorders and those on diuretic therapy are more likely to have abnormal electrolytes and require measurement preoperatively.

Coagulation panel

Coagulation tests are performed to detect a predisposition for perioperative bleeding. The most common tests performed are the prothrombin time (PT) and partial thromboplastin time (PTT). The incidence of abnormal values in routine testing ranges from <1% to 6.5%. If liver disease is suspected in the patient scheduled for laparoscopic cholecystectomy, these tests are indicated.

Liver function tests

Liver function tests are usually elevated in patients with biliary obstruction due to biliary calculi or cholangitis. In cholangitis, which is a medical emergency, all liver function tests (AST, ALT, ALP, GGTP) are elevated. In patients with choledocholithiasis, the most sensitive test is the GGTP, which is elevated in 92.2% of patients. Alkaline phosphatase is elevated in 74.4% of patients, while the AST is the least sensitive (50.8%). Serum bilirubin will be increased, with elevation of conjugated bilirubin. Test results may be in the normal range in a small percentage of patients with biliary stones (5%)

Imaging tests

These tests are performed preoperatively to confirm the diagnosis of gallbladder disease. Sonography is a sensitive diagnostic modality in acute cholecystitis, The usual findings include dilatation of the gallbladder, thickening of the gallbladder wall, and pericholecystic fluid collection.

CT scans are more sensitive and specific in depiction of inflammation of the gallbladder, revealing pericholecystic abscesses and gas or calculi outside the gallbladder.

Magnetic resonance cholangiopancreatography (MRCP) is a highly accurate noninvasive test that provides anatomic information on the biliary tract and avoids the risks of the endoscopic procedure (ERCP).

The ERCP is the gold standard for preoperative diagnosis of choledocolithiasis but is associated with the risk (15%) of pancreatitis and cholangitis, perforation of bile duct or duodenum, and bleeding.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

In addition to the usual anesthetic challenges posed by ambulatory surgery involving rapid recovery and control of postoperative pain and nausea and vomiting, laparoscopic cholecystectomy presents additional physiological alterations related to the pneumoperitonium. Although laparoscopic cholecystectomy with regional anesthesia has been reported, the anesthetic technique of choice is usually general anesthesia because of patient comfort concerns and cardiorespiratory effects of the pneumoperitonium.

Regional anesthesia

Neuraxial

The regional anesthetic techniques for laparoscopic cholecystectomy that have been described include lumbar and thoracic epidural and subarachnoid block with sensory blockade between T3-T5, with and without the use of intrathecal opioids.

Benefits

Patients receiving subarachnoid blockade seem to have a prolonged analgesic effect and tend to require less opioid analgesics postoperatively.

Complications such as sore throat related to tracheal intubation and muscle pain due to succinylcholine are avoided.

Drawbacks

Pneumoperitoneum will cause a rise in arterial CO2 and respiratory acidosis, which may predispose the patient to cardiac arrhythmias. Hypercarbia, however, is not a consistent finding in the reported series and may be related to the type and dosage of supplemental sedation administered.

Incomplete block or an inadvertent high block may require tracheal intubation and ventilation.

Inadvertent dural puncture during an intended epidural technique and resultant headache may result in prolonged hospital stay.

Issues

It has been suggested that the use of nitrous oxide for insufflation and maintaining intra-abdominal pressures in the range of 10 mm Hg results in less peritoneal irritation and neck and shoulder pain complaints, which occur in 30%-50% of patients. In most cases these symptoms may be managed with small doses of sedatives, but in some patients conversion to general anesthesia is necessary.

General Anesthesia

The majority of laparoscopic cholecystectomies are performed with general anesthesia.

Benefits

Following CO2 insufflation of the peritoneal cavity, the gas is absorbed and the end-tidal and arterial concentrations of CO2 will increase. Increasing minute ventilation during general anesthesia will maintain arterial CO2 within normal range. The pneumoperitonium also reduces the functional residual capacity and lung compliance, but the reverse Trendelenburg position during surgery may counter balance these changes.

Drawbacks

The combination of pneumoperitonium and the head-up position for laparoscopic cholecystectomy results in a decrease in venous return and cardiac output and an increase in systemic vascular resistance and mean arterial pressure. While these effects are well tolerated by healthy patients, they may be unpredictable in patients with limited cardiac reserve or reduced intravascular volume status, who may suffer adverse consequences if they are not closely monitored and treated promptly. Laparoscopic cholecystectomy has been performed successfully in patients with an ejection fraction of 15%, awaiting cardiac transplantation.

Opioid analgesics are often administered intraoperatively to supplement inhalation agents and may contribute to postoperative nausea and vomiting. Judicious use of opioids and combination with nonopioid analgesics is a very effective anesthetic alternative. Use of a total intravenous technique with propofol has been shown to have a lower incidence of postoperative nausea and vomiting compared to inhalation agents. Remifentanil has been shown to be very effective at controlling the hemodynamic responses to laparoscopy at a low dose range, but has a short duration of action, necessitating the administration of a small dose of long-acting opioid at the end of surgery.

Other issues

Nitrous oxide has been used during laparoscopic cholecystectomy without significant bowel distention. However, it is unclear if it poses a fire hazard, since it has been shown in the laboratory that following 2 hours of administration, the concentration exceeded 29%, a level that will support combustion.

Systemic lidocaine infusion (bolus 1.5 mg/kg followed by 2 mg/kg/hr) during laparoscopic cholecystectomy has been associated with a 10% reduction in intraoperative desflurane and significantly less postoperative fentanyl and shorter time to meet discharge criteria.

Airway concerns

Outpatients who present for laparoscopic cholecystectomy may have high volumes of gastric contents and together with the increased intra-abdominal pressures maybe at increased risk of passive regurgitation of gastric contents. The presence of a cuffed endotracheal tube may decrease the chances of intraoperative aspiration.

Monitored Anesthesia Care

Sedation/analgesia is not an appropriate anesthetic for laparoscopic cholecystectomy.

6. What is the author's preferred method of anesthesia technique and why?

General anesthesia is the preferred technique for most laparoscopic cholecystectomies because of the ability to control and treat the hypercarbia that may result from the insufflation of carbon dioxide. The shoulder discomfort associated with diaphragmatic irritation due to pneumoperitoneum may require large doses of opiates and sedatives and result in respiratory depression. Furthermore, the use of NMBAs during general anesthesia may facilitate the creation of an adequate pneumoperitoneum and aid surgical dissection.

What prophylactic antibiotics should be administered?

The average rate of perioperative infection with laparoscopic cholecystectomy ranges between 0.4% and 6.3% and the use of perioperative antibiotic prophylaxis is controversial. The Surgical Care Improvement Project (SCIP) guidelines do not recommend routine preoperative antibiotics for patients undergoing laparoscopic cholecystectomy. However, most surgeons administer antibiotics to those patients who have risk factors for perioperative infection, including age over 60 years, common bile duct disease, acute cholecystitis, jaundice, or previous biliary tract surgery. Cephazolin is the drug of choice, with clindamycin as an alternate in the patient with a penicillin allergy.

What do I need to know about the surgical technique to optimize my anesthetic care?

During most of the surgical procedure the patient will be in steep reverse Trendelenberg position, which may compromise venous return and cardiac output. Close attention to blood pressure monitoring and fluid therapy is necessary, especially in patients with cardiac disease. Following creation of the pneumoperitoneum, the Veress needle is inserted in the subumbilical area. The majority of visceral and vascular injuries occur at this time and attention to the patient's vital signs and the surgical field will allow early detection of these injuries. Any unexplained hypotension must be brought to the attention of the surgeon, since bleeding in the retroperitoneum may not be readily visible. Most surgeons use additional ports for optical and operating devices, but single access laparoscopic cholecystectomy and cholangiography has been described. Many surgeons are now adopting this procedure for esthetic reasons.

What can I do intraoperatively to assist the surgeon and optimize patient care?

In most cases the surgeon will require the patient's arms to padded and secured by the side to allow easy access to the surgical field. Placement of a nasograstric tube to decompress the stomach will facilitate surgical dissection. In cases where diaphragmatic excursions might make dissection of the gallbladder difficult, the pattern of ventilation can be altered to minimize the movement. It is important to pay close attention to changes in end-tidal carbon dioxide (ETCO2) levels, especially in prolonged surgeries or in cases with subcutaneous emphysema. It is important to communicate these changes to the surgeon also. Gas emboli occur frequently during dissection of the gallbladder bed and are usually manifested by a sudden drop in ETCO2 along with hypotension. These changes must be communicated to the surgeon at once so that appropriate resuscitative measures can be instituted promptly.

What are the most common intraoperative complications and how can they be avoided/treated?

Routine laparoscopic cholecystectomy is associated with a perioperative mortality rate of <1% and morbidity is in the range of 2%-17%, usually due to patient-related factors. Advanced patient age, longer duration of surgery, and acute cholecystitis increase postoperative morbidity and length of hospital stay.

Pulmonary complications

Hypoxemia during laparoscopic cholecystectomy may be the result of the decreased functional residual capacity due to the pneumoperitoneum or endobronchial intubation as a result of the cephalad movement of the carina with abdominal distention. A reduction in cardiac output will also result in hypoxemia. Extraperitoneal migration of the CO2 can give rise to pneumothorax (0.03%) or pneumomediastinum (0.08%). The migration of gas may occur through a congenital defect in the diaphragm, but may also be caused by diaphragmatic injury or barotrauma. In most cases the pneumothorax is on the right side and is associated with a drop in SaO2 and an increase in ETCO2 and airway pressure. The patient usually is hypotensive and tachycardic. Carbon dioxide gas is a highly soluble and is quickly absorbed from the pleural cavity. If the patient is hemodynamically stable, chest tube placement may not be required.

Subcutaneous emphysema occurs in 2-12 per 1000 cases and may extend into the head, neck, and chest. Hypercarbia is associated with an increase in vascular resistance and intracranial pressure, and the accompanying acidosis will increase the tendency for cardiac arrhythmias.

Pneumonia (0.07%) and atelectasis (25%) is much less frequent following laparoscopic versus open cholecystectomy.

Cardiovascular complications

Cardiac arrhythmias are the most common cardiac complication during laparoscopy and are in the range of 47%. They are usually ventricular ectopy or tachyarrhythmias as a result of hypercarbia, acidosis, and increased sympathetic stimulation. Bradyarrhythmias may result from vagal stimulation due to stretching of the peritoneum with insufflation and respond to prompt desufflation and anticholinergic agents. Other cardiac complications include hypotension, hypertension, and cardiac arrest. The hemodynamic changes associated with the pneumoperitoneum may be minimized by limiting the intra-abdominal pressure and the degree of reverse Trendelenburg. In patients with significant cardiac disease who may require pharmacologic interventions to maintain perioperative hemodynamic status, invasive monitoring may be indicated.

Effects on perfusion of other organs

Pneumoperitoneum is associated with a decrease in gastric, intestinal, renal, and liver blood flow. There is an inverse relationship between the intra-abdominal pressure and renal perfusion. Renal vascular resistance increases dramatically following CO2 insufflation and there is an increase in antidiuretic hormone release and activation of the renin-angiotensin-aldosterone system. Insufflation with warm gas causes renal vasodilation and may be beneficial in patients with compromised renal function. The renal effects persist for about two hours postoperatively.

The increased intra-abdominal pressure also compromises the circulation to the stomach, duodenum, jejunum, colon, and liver. Liver enzymes are often elevated following laparoscopic cholecystectomy.

Unique to the procedure

Gas embolism

This is a well-documented phenomenon and is potentially lethal. Transesophageal echocardiography has documented that 68% of patients undergoing laparoscopic cholecystectomy have CO2 emboli in the right heart chambers and transcranial Doppler has demonstrated that CO2 bubbles reach the cerebral circulation. Hypovolemia and reverse Trendelenburg position during laparoscopic cholecystectomy have been shown to be risk factors for CO2 gas embolism. Management requires prompt diagnosis, discontinuing further insufflation, and supportive therapy. Aspiration of the emboli may be attempted.

Surgical complications

The incidence of injuries at the time of insertion of the trocars or the Veress needle comprise the majority of surgical complications and are in the range of 0.2%. The incidence of major vascular injuries (aorta, iliac, mesenteric, and lumbar vessels, inferior vena cava) is in the range of 0.07%-0.4%. Minor vascular injuries (epigastric, mesenteric, and omental vessels) are in the range of 0.1%-1.2%. The mortality rate from these injuries is 0.05%-0.2%.

Bowel injuries are usually also related to trocar inserion and range from 0.07% to 0.7%. These injuries may not be detected at the time of surgery.

Spillage of gallstones occurs in 10%-30% of laparoscopic cholecystectomies. This rarely results in serious complications but may result in intra-abdominal abscess and sinus formation. Injury to the common bile duct is the most frequently reported complication (0.125%-0.25%). Seventy-eight percent of surgical complications that result in litigation following laparoscopic cholecystectomy relate to bile duct injuries, followed by vascular injuries (7%), and bowel injuries (2%). These injuries are frequently missed at the time of surgery and result in a high rate of mortality, usually due to sepsis.

The rate of conversion from laparoscopic to open cholecystectomy is in the range of 1%-30%, and the commonest reason is difficulty in displaying the anatomy. Other independent risk factors include advanced patient age (>60 years), obesity (>65 kg), male gender, previous upper abdominal surgery, HbA1C >6, acute cholecystitis, and junior surgeon.

b. If the patient is intubated, are there any special criteria for extubation?

Following surgery, patients can be extubated when the following standard criteria are met: absence of fade with TOF or tetanic stimulation (50 Hz) with peripheral nerve stimulation.

c. Postoperative management

Postoperative pain management has a significant effect on the quality of life following surgery. Laparoscopic cholecystectomy is a short procedure and to be effective, analgesics must be administered in sufficient time for maximum benefit, often preoperatively. The pain following laparoscopic cholecystectomy is multidimensional and optimal analgesic management will involve a multimodal approach. While several modalities have been found to be effective in relieving the somatic and visceral components of pain following laparoscopic cholecystectomy, the only effective treatment for the referred shoulder pain that has been shown to be successful is the use of low insufflation pressures (7-9 mm Hg) intraoperatively.

What analgesic modalities can I implement?

Opioid analgesics are associated with several adverse effects that are associated with prolonged recovery time, and it has been recommended that only short-acting opioids be administered intraoperatively. When opioid analgesics are necessary, they should be titrated carefully to avoid adverse effects. The NSAIDs and COX-2 inhibitors are effective analgesics for laparoscopic cholecystectomy and should be administered around the clock. They have an opioid-sparing effect, which results in a lower incidence of postoperative nausea and vomiting.

The effects of preoperative administration of steroids is controversial. A single dose of dexamethasone (8 mg) administered 90 minutes prior to surgery has been shown to reduce postoperative pain by 50%. In the studies where it has not been shown to have an analgesic effect, it has been given immediately prior to incision and pain was not a primary outcome. The single dose does not affect postoperative healing or infection.

Low-dose gabapentin (300 mg) administered 2 hours prior to laparoscopic cholecystectomy has been shown to effectively reduce postoperative pain scores and reduce opioid consumption by 17% compared with tramadol and 37% compared with placebo. Pregabalin (50-75 mg) administered 1 hour prior to surgery resulted in improved postoperative analgesia in the early recovery period following laparoscopic cholecystectomy, without clinically significant adverse side effects. When administered twice a day for 7 days, it lowers opioid consumption for the duration.

Clonidine inhibits the release of substance P from the dorsal horn, but studies involving the effect of preoperative administration of clonidine in laparoscopic cholecystectomy are not conclusive and do not support its routine use.

Intraperitoneal local anesthetic is controversial with some studies showing significant analgesic effect in the early recovery phase. The most commonly used local anesthetic is 0.25%-0.55% bupivacaine, and the usual volume administered is 30 mL. Early administration may be more effective than instillation at the end of surgery; however, routine use is not recommended. Infiltration of local anesthetic into the port sites results in significant analgesia in the first 2 hours following surgery, with an opioid-sparing effect. Twenty to 30 mL of bupivacaine is commonly used. If the two modalities are combined, the total dose of local anesthetic should not exceed the toxic range. The addition of epinephrine will decrease systemic absorption and increase the safety.

Of the NMDA antagonists, only dextromethorphan (40 mg IM) given 30 minutes prior to incision has been shown to result in improved postoperative analgesia. The effects of low-dose ketamine are controversial.

Although epidural analgesia is effective following laparoscopic cholecystectomy, the procedure is usually performed on an outpatient basis and it is therefore not recommended. Paravertebral block of T5-6 has been used for postoperative analgesia in patients undergoing laparoscopic cholecystectomy. While the procedure does seem to provide good analgesia, it is associated with a 0.125% risk of pneumothorax and 0.2% risk of pleural puncture.

What level bed acuity is appropriate?

Laparoscopic cholecystectomy is routinely performed on an ambulatory basis. Studies comparing ambulatory and inpatient procedures reveal that the unplanned admission rate in the ambulatory group is comparable to the rate of prolonged hospitalization of inpatients. There is no significant difference between the readmission rates of the two groups, and the quality-of-life indicators were similar for the ambulatory and inpatients. Cost effectiveness was better for ambulatory procedures because of the shorter hospital stay.

What are common postoperative complications, and ways to prevent and treat them?

Increased postoperative morbidity and increased length of hospital stay has been shown to be related to increased duration of surgery (>2 hours), advanced age (>60 years), and the presence of acute cholecystitis.

Following laparoscopic cholecystectomy pulmonary impairment due to diaphragmatic dysfunction may persist for up to 24 hours. Postoperativerespiratory failure has been reported in a patient with paralysis of the hemidiaphragm due to radical neck surgery.

General anesthesia results in pulmonary atelectasis in patients, that is more pronounced in obese patients. The extent of atelectasis has been evaluated by computed tomography 24 hours after laparoscopic surgery, and it was noted that the amount of atelectasis remained unchanged in the morbidly obese patients, while there was complete resolution in non obese patients.

Subcutaneous emphysema due to extraperitoneal insufflation is a common complication with an incidence of 0.4%-2%. The gas may collect in the subcutaneous tissues or between the fascia and the peritoneum. This is associated with a gradual and sometimes dramatic rise in ETCO2 intraoperatively, despite adequate ventilation. However, because of the solubility of CO2, the gas is absorbed very quickly once insufflation ceases.

Increased intra-abdominal pressures may result in femoral vein compression and decreased femoral vein blood flow, predisposing the patient to deep vein thrombosis and pulmonary embolism. The incidence of pulmonary embolism following laparoscopic cholecystectomy is in the range of 0.016%. Increased age, body mass index, and duration of pneumoperitoneum have been found to correlate with significant activation of coagulation and fibrinolysis reflected by a significant decrease in APTT and antithrombin III and a decrease in D-dimers. Patients in those categories are more vulnerable to development of postoperative deep vein thrombosis. Early postoperative ambulation will reduce venous stasis.

Transient alteration of liver function tests is seen following laparoscopic cholecystectomy. Seventy-three percent of patients will have an increase in aspartate aminotransferase (AST) and 82% will have an increase in alanine aminotransferase (ALT) , while billirubin is increased in 14% of patients and is usually an increase in unconjugated bilirubin. This increase in unconjugated bilirubin may be a consequence of blood transfusions, underlying hemolytic disorders, resorbing hematomas, drug effects, or Gilbert's syndrome.

Treatment is directed toward the underlying condition. An increase in conjugated bilirubin is the result of either intrahepatic or extrahepatic disorders. Extrahepatic biliary obstruction must be considered in all patients with conjugated hyperbilirubinemia after laparoscopic cholecystectomy. Abdominal sonography is the best screening test to assess for obstruction. Biliary strictures or leaks may require ERCP with balloon dilation of strictures or stent placement for strictures and leaks resulting from transected bile ducts. Percutaneous drainage and antibiotic therapy is recommended in patients with bile leaks and large collections of intra-abdominal fluid. Surgery may be required for patients with strictures or leaks that are not amenable to either endoscopic or percutaneous intervention.

(Comprehensive guidelines for physicians involved in the perioperative care of patients undergoing non-cardiac surgery, based on a framework of the cardiac risk involved in a variety of patient and surgical situations.)

(A review of the literature related to postoperative analgesic management following laparoscopic cholecystectomy, suggesting a multimodal approach with nonopioid analgesics and the use of opioids only when other techniques are insufficient.)

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